Antennas used in analyzing electromagnetic radiation emissions from and the immunity of various devices to such radiation should have relatively broad band or so-called frequency independent operating capability. Such antennas should, also, desirably have minimum physical size and mechanical simplicity for portability as well as cost considerations. For a considerable portion of the frequency band used in the above-mentioned electromagnetic compatibility testing, as well as in some communications applications, a half wave length dipole antenna is physically too large for many operating environments. In this regard, physical size restraints often require the use of so-called electrically small antennas or antennas that resonate at a resonance frequency corresponding to about 0.1 wave length of the emitted or received signal.
Certain improvements in shaped element dipole antennas for applications in electromagnetic compatibility testing as well as in certain communications applications, have been provided by the invention described and claimed in the above-referenced patent application. An antenna according to the invention in the above-referenced patent application includes a folded triangular element or "bowtie" dipole antenna which has been advantageous for minimizing antenna losses at the lower frequencies of the antenna frequency range than is possible with a conventional folded wire dipole antenna of the same physical size. Performance improvements for antennas which utilize the folded triangular shaped element dipole antenna in combination with a log periodic dipole array have also been realized with the antenna invention of the above-referenced patent application, which application is incorporated herein by reference. However, it has also been determined that under certain operating conditions, the folded triangular element antenna used alone, in combination with a log periodic antenna array or in combination with a single plane triangular shaped element antenna or a second folded triangular shaped element antenna may experience a phenomena known as mutual impedance which manifests itself as interference or parasitic coupling and caused by the folded triangular element antenna or the single plane triangular element antenna or the second folded triangular element antenna of an array. However, in accordance with the present invention, it has been discovered that performance improvements may be obtained along the lines disclosed in the above-referenced patent application by providing a triangular element antenna without the complete folded configuration but constructed in accordance with the invention as described hereinbelow.